They’re dancing, but it’s weird: the smell is of engines, oil and worn metal; the crowd occupies the hold of an old German merchant ship docked in London, the MS Stubnitz. The DJ isn’t really a DJ: she’s a Colombian composer and programmer called Alexandra Cárdenas. She has no decks. Instead, she’s working on a laptop. A projection behind shows about 20 lines of code, which she is toying with, stripping some away, modifying the parameters of others. The minimal techno starts piling up, reversing on itself. Complex rhythms emerge, fall away, then come back stronger, energising the crowd. Cárdenas is completely lost in the music. This is an « algorave », where humans dance to algorithms.
This is Cárdenas’s first algorave; she only heard the term in September last year, at a music coding festival in Mexico City, where she lives. « It was very rhythmical — it was the first time I wanted to dance to a live code session, » she says. But the 37-year-old composer says the scene is growing. « It’s becoming a movement. I know we are small now, but I see it growing so strong and fast. It’s a point where technology, geek stuff and this hacker philosophy come together with clubbing. »
Algorave « started as a joke », according to Alex McLean, a computer-music researcher and one-third of a band called Slub that’s been live coding for 13 years. He came up with the term while driving to a gig in Nottingham with his friend Nick Collins (who plays « datapop » under the name Sick Lincoln) in late 2011. « We tuned into a pirate station playing happy hardcore, and we thought it would be good to program some rave music. » Since then, McLean has organised eight informal algoraves around the world. « It’s kind of changing the way people think about computer music, » the 38-year-old says. « And also breaking the limits of what electronic music can be. »

In London, the music veers between the sublime and the cacophonic; at the end, one audience member — and she’s entirely serious — shouts: « Play something good! » Algorave is messy, but that’s partly the point: these are not the pristine algorithms that fetch your search results on Google; they’re built live, for a crowd. As the algorave site says: « It’s up to the good people on the dancefloor to help the musicians make sense of this and do the real creative work in making a great party. »